In the processing and preparation of parts of poultry and animals such as poultry thighs and drumsticks for sale and consumption in the retail market, such as in restaurants and grocery stores, it is highly desirable to package and serve the meat with the bones removed. Deboned meat can be easily cut-up and used in sandwiches or other food products where it is desirable to have the bones previously removed prior to cooking and serving.
An additional advantage of removing the bones from the meat during processing and before cooking is that the bones do not have to be cooked with the meat, thereby conserving heat energy. Further, the removal of the bone prior to cooking allows the bone to be saved and used for bone meal or related products.
In the past, automated processes have been developed for the removal of meat from the bone of a poultry part, such as from the bones of a poultry thigh and/or drumsticks, by engaging the bone with a scraping tool and scraping along the length of the bone. For example, U.S. Pat. Nos. 3,672,000, 4,327,463, 4,495,675, and 4,736,492 disclose deboning apparatus having two or more notched scraping blades which engage the bone. The blades are closed about the bone with the notches of the blades straddling the bone, and the bone is moved longitudinally through the blades. As the bone is moved through the notched blades, the blades progressively scrape the meat from the bone.
However, the raw meat has a tendency to cling tightly to the bone. Consequently, it is necessary for the scraper blades to engage the bones in tight frictional contact to ensure the meat is completely scraped from the bone. A problem that arises with such prior art deboners is that the blades engaging the bone sometimes inadvertently gouge or chip and sometimes crack the bones as they scrape the bones. This creates bone fragments that can become lodged in the stripped meat, which creates a serious health risk to the ultimate consumer who expects that when he or she purchases a "boneless" product, it is indeed completely boneless.
In order to avoid the creation of bone fragments during the deboning process, apertured elastic meat stripper disks have been substituted for the scraper blades. The bone is pushed longitudinally through the aperture of the disk and the resilient disk retards the movement of the meat, thereby separating the meat from the bone. U.S. Pat. No. 4,811,456 teaches the use of such elastic disks.
Additionally, U.S. Pat. No. 5,173,076 discloses an automated deboning apparatus which includes a series of elastic stripping disks, each of which is mounted adjacent and moves with a conveyor tray on which a poultry part is received and moved about a processing path. As the poultry part is moved along the processing path, the bone is urged through openings in the stripper disks, whereupon the meat is progressively stripped from its bone. Such a system is, however, limited in size and in the number of deboning modules included therewith, which limits the production capacity of the apparatus. Conventional deboning apparatus also generally are not readily expandable to increase the number of parts that can be processed as needed.
As outlined above, the U.S. Pat. Nos. 3,672,000, 4,327,463, 4,495,675, 4,736,492, 4,811,456 and 5,173,076 describe devices for deboning wing or leg parts such as thighs and drumsticks, provided with scrapers or discs defining an aperture through which the part to be deboned passes, thereby scraping off the meat from the bone. Other similar filleting devices are available on request under the type designation MK40, MK80, 025, D30, D40 and D90. These automatic machines work with the aid of the so-called diaphragm-principle, whereby the bone is pushed out of the meat with the aid of a pin.
Applicants' as yet unpublished European patent application 97.200.019.4, (the contents of which shall be deemed incorporated by reference herein) and U.S. patent application Ser. No. 08/782,876, filed Jan. 14, 1997, (the contents of which shall be deemed incorporated by reference herein) describe an improved deboning device for legs, particularly thighs and drumsticks of big birds, such as turkeys. This device includes a chain conveyer revolving in a vertical plane, provided with a series of, in the direction of conveyance, transversely placed carrier trays for holding the poultry legs. In the deboning process, a pusher rod pushes the leg, while lying on the tray, against a scraping disc. Subsequently the pusher rod is further advanced in transverse direction to force the bone in a diaphragm manner through an aperture in the scraping disc. The meat is then retained between the scraper disc and the sleeve. After the meat has been separated from the bone in this manner, the trays are transported back to the small gear wheel along the lower run, to be returned to the loading track.
Although the deboning machine just described can work reliably when filleting most parts of legs (three pieces) and wings (two pieces), occasional difficulties occur when filleting drumsticks of big birds, such as turkeys. The reason for the difficulty is that the connection between muscular tissue and bone is such that scraping along the bone is insufficient to completely separate the meat from the bone. In an attempt to remedy this problem, most poultry processing operators make an incision by hand during loading. This, however, is a complicating factor to the entire process which thus takes more time. Correspondingly, the cost of the poultry increases. Moreover, the act of incision creates a potential risk of injury for the operator. Also, there is great room for inconsistency or error.
Accordingly, it can be seen that it would be highly desirable to provide a method and apparatus for cleanly and completely scraping the meat from the drumsticks of large birds, such as poultry, without the complication of cutting the part during loading, and with the apparatus being expandable to enable a greater quantity of poultry parts to be processed.